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Xuping Li, Gleb Baryshnikov, Chao Deng, Xiaoyan Bao, Bin Wu, Yunyun Zhou, Hans Ågren, Liangliang Zhu
Visualized sensing through fluorescence signals is a powerful method for chemical and physical detection. However, the utilization of fluorescent molecular probes still suffers from lack of precise signal self-calibration in practical use. Here we show that fluorescence and thermally activated delayed fluorescence can be simultaneously produced at the single-molecular level. The thermally activated delayed fluorescence serves as a sensing signal with its wavelength and lifetime both altered correlating to polarity, whereas the fluorescence always remains unchanged as an internal reference...
February 13, 2019: Nature Communications
Zaijun Chen, Theodor W Hänsch, Nathalie Picqué
Mid-infrared high-resolution spectroscopy has proven an invaluable tool for the study of the structure and dynamics of molecules in the gas phase. The advent of frequency combs advances the frontiers of precise molecular spectroscopy. Here we demonstrate, in the important 3-µm spectral region of the fundamental CH stretch in molecules, dual-comb spectroscopy with experimental coherence times between the combs that exceed half an hour. Mid-infrared Fourier transform spectroscopy using two frequency combs with self-calibration of the frequency scale, negligible contribution of the instrumental line shape to the spectral profiles, high signal-to-noise ratio, and broad spectral bandwidth opens up opportunities for precision spectroscopy of small molecules...
February 12, 2019: Proceedings of the National Academy of Sciences of the United States of America
YiLei Fan, XiangWei Cheng, Guiying Xue, JianBing Wu, ZhongPing Huang
The present paper reported a hybrid structure for the optical recognition of PA (picric acid). This dye-MOF structure, named as R6h@EuBTC, consisted of a supporting matrix based on rare earth MOF and a sensing probe based on rhodamine dye, which was confirmed using XRD, IR, thermal and photophysical analysis. R6h@EuBTC's rhodamine absorption in visible region was enhanced by increasing PA concentrations, showing obvious color change and consequently colorimetric sensing. R6h@EuBTC's rhodamine emission component was increased by increasing PA concentrations, while its Eu emission component was slightly quenched by increasing PA concentrations, which offered self-calibrated sensing signals for ratiometric fluorescent sensing...
January 17, 2019: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Michael Chen, Zachary F Phillips, Laura Waller
Differential Phase Contrast (DPC) microscopy is a practical method for recovering quantitative phase from intensity images captured with different source patterns in an LED array microscope. Being a partially coherent imaging method, DPC does not suffer from speckle artifacts and achieves 2× better resolution than coherent methods. Like all imaging systems, however, DPC is susceptible to aberrations. Here, we propose a method of algorithmic self-calibration for DPC where we simultaneously recover the complex-field of the sample and the spatially-variant aberrations of the system, using 4 images with different illumination source patterns...
December 10, 2018: Optics Express
Zhan Zhou, Jiapei Gu, Yuze Chen, Xiaoxia Zhang, Haixia Wu, Xiaoguang Qiao
Bacillus anthracis spore causes anthrax to seriously threaten human health and even cause death. 2,6-Pyridinedicarboxylic acid (DPA) is a unique biomarker because it is a major component of Bacillus anthracis spore. Herein, we design europium functionalized silicon quantum dots as a ratiometric fluorescent nanoprobe to detect DPA with high sensitivity and selectivity. With the addition of DPA, the red emission peaks were observed at 618 nm. The novel probe enables ratiometric and sensitive DPA detection over nanomolar concentrations (as low as 1...
December 21, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Gihoon Byun, H C Song, J S Kim
This paper compares the localization performance of array invariant (AI) and matched field processing (MFP) using a ship of opportunity radiating random noise (200-900 Hz) and a tilted vertical array. AI is a deterministic approach to source-range estimation (i.e., depth-blind), exploiting the dispersion characteristics of broadband signals with minimal/no knowledge of the environment in shallow water. It involves time-domain plane-wave beamforming to separate multiple coherent arrivals (eigenrays) in beam angle and travel time, called "beam-time migration," from which the source range is directly estimated...
December 2018: Journal of the Acoustical Society of America
Marco Montecchi
Solar reflectance is one of the most important parameters characterizing the mirrors used to redirect the solar radiation toward a receiver in concentrating solar power plants. In Solar Power and Chemical Energy Systems (SolarPACES) Task III, an international group of experts is drafting the reflectance guidelines and debating the hard task of measuring off-normal near-specular solar-reflectance. Because of the lack of suitable commercial instruments, several research institutes are studying and setting up special equipment...
December 2018: Review of Scientific Instruments
Nithya Velusamy, Natesan Thirumalaivasan, Kondapa Naidu Bobba, Arup Podder, Shu-Pao Wu, Sankarprasad Bhuniya
We have developed a FRET-based fluorescent probe (PHS1) as a combination of two different fluorophores (coumarin and naphthalimide); which can detect both exogenous and endogenous H2 S and H2 O2 in live cells through multicolor images. The precise overlap between UV-absorption of naphthalimide and the emission band of coumarin in probe PHS1 allows the acquisition of the self-calibrated information of dual analytes through FRET-based imaging. The UV-Vis absorption (λabs 390 nm) and fluorescence emission (λem 460 nm) of probe PHS1 in the presence of H2 O2 are increased ∽35- fold and ∽15-fold respectively...
December 26, 2018: Journal of Photochemistry and Photobiology. B, Biology
Jason Clark
A systemic problem for microelectromechanical systems (MEMS) has been the large gap between their predicted and actual performances. Due to process variations, no two MEMS have been able to perform identically. In-factory calibration is often required, which can represent as much as three-fourths of the manufacturing costs. Such issues are challenges for microsensors that require higher accuracy and lower cost. Towards addressing these issues, this paper describes how microscale attributes may be used to enable MEMS to accurately calibrate themselves without external references, or enable actual devices to match their predicted performances...
December 13, 2018: Sensors
Dimitris A Herrera, Toby R Ault, John T Fasullo, Sloan J Coats, Carlos M Carrillo, Benjamin I Cook, A Park Williams
The Caribbean islands are expected to see more frequent and severe droughts from reduced precipitation and increased evaporative demand due to anthropogenic climate change. Between 2013 and 2016, the Caribbean experienced a widespread drought due in part to El Niño in 2015-2016, but it is unknown whether its severity was exacerbated by anthropogenic warming. This work examines the role of recent warming on this drought, using a recently developed high-resolution self-calibrating Palmer Drought Severity Index data set...
October 16, 2018: Geophysical Research Letters
Wei Liu, Xing Dai, Yanlong Wang, Liping Song, Lin-Juan Zhang, Duo Zhang, Jian Xie, Long Chen, Juan Diwu, Jianqiang Wang, Zhi-Fang Chai, Shuao Wang
Traditional analytical methods of thorium contamination suffer from several disadvantages such as time-consuming procedure and equipment-intensive nature, leading to substantial challenges in rapid and onsite monitoring of thorium concentration in complex natural water systems. We report here the first case of luminescent metal organic framework based probe (ThP-1) for highly sensitive and selective self-calibrated sensing of Th4+ contamination in natural fresh water media with a notably facilitated detection procedure...
December 5, 2018: Environmental Science & Technology
Caifeng Ding, Yunxia Li, Lei Wang, Xiliang Luo
A sensitive and reliable bimodal electrochemiluminescent (ECL) system based on CdTe Quantum Dots (QDs) and luminol as double luminophores is constructed. CdTe QDs tagged with the aptamer (CdTe-Apt 2) of cancer cells are used as the detection signal, while luminol molecules are used as internal standards. The electrodeposited polyaniline based conducting polymer hydrogel (CPH) on the electrode surfaces improves the biocompatibility and conductivity of the sensing interfaces effectively. Furtherly, electron transfer is probably much easier when luminol and coreactant potassium persulfate (K2S2O8) immobilized in the CPH compared to that in solution...
November 30, 2018: Analytical Chemistry
Xueping Ju, Changxiang Yan, Junqiang Zhang, Bin Yang, Wenhe Xing
Retardation errors of high-order retarders will decrease the accuracy of a channeled spectropolarimeter. Taniguchi et al. have proposed a self-calibration method to calibrate the retardations [Opt. Lett.31, 3279 (2006)OPLEDP0146-959210.1364/OL.31.003279]; however, they do not take into account the inevitable alignment errors of high-order retarders. In this paper, an adaptive correction method with immunity to alignment errors is proposed to reduce the effects of temperature variation on retardations. By separating and analyzing the amplitude terms and phase terms contained in the measurement data, the phase terms are utilized to correct the retardations, which makes the effectiveness of this adaptive correction method immune to the inevitable alignment errors of high-order retarders...
October 1, 2018: Applied Optics
Stanislas Rapacchi, Thomas Troalen, Zakarya Bentatou, Morgane Quemeneur, Maxime Guye, Monique Bernard, Alexis Jacquier, Frank Kober
PURPOSE: To accelerate cardiac cine at 7 tesla using simultaneous multi-slice (SMS) acquisition with self-calibration to resolve misalignment between calibration and imaging data due to breathing motion. METHODS: A spoiled-gradient echo cine sequence was modified with radiofrequency phase-cycled SMS excitations. A Fourier encoding strategy was applied along the cardiac phase dimension to allow for slice untangling and split-slice GRAPPA calibration. Split-slice GRAPPA was coupled with regular GRAPPA (SMS-GRAPPA) and L1-SPIRiT (SMS-L1SPIRiT) for image reconstruction...
November 19, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Peng Sun, Nai-Guang Lu, Ming-Li Dong, Bi-Xi Yan, Jun Wang
Highly accurate and easy-to-operate calibration (to determine the interior and distortion parameters) and orientation (to determine the exterior parameters) methods for cameras in large volume is a very important topic for expanding the application scope of 3D vision and photogrammetry techniques. This paper proposes a method for simultaneously calibrating, orienting and assessing multi-camera 3D measurement systems in large measurement volume scenarios. The primary idea is building 3D point and length arrays by moving a scale bar in the measurement volume and then conducting a self-calibrating bundle adjustment that involves all the image points and lengths of both cameras...
November 15, 2018: Sensors
Minruihong Wang, Huiliang Cao, Chong Shen, Jin Chai
This paper proposes an effective method to calibrate the microelectromechanical systems (MEMS) vibratory gyroscope based on the virtual Coriolis force. This method utilizes a series of voltage signals to simulate the Coriolis force input, and the gyroscope output is monitored to obtain the scale factor characteristics of the gyroscopes. The scale factor and bias parameters of the gyroscope can be calibrated conveniently and efficiently in the sense-mode open loop. The calibration error of the scale factor based on the turntable and the virtual Coriolis force method is only 1...
June 28, 2018: Micromachines
Yue Wang, Xiangjun Wang, Zijing Wan, Jiahao Zhang
Nowadays, binocular stereo vision (BSV) is extensively used in real-time 3D reconstruction, which requires cameras to quickly implement self-calibration. At present, the camera parameters are typically estimated through iterative optimization. The calibration accuracy is high, but the process is time consuming. Hence, a system of BSV with rotating and non-zooming cameras is established in this study, in which the cameras can rotate horizontally and vertically. The cameras' intrinsic parameters and initial position are estimated in advance by using Zhang's calibration method...
October 29, 2018: Sensors
T Thiele, Y Lin, M O Brown, C A Regal
Atomic magnetometry is one of the most sensitive ways to measure magnetic fields. We present a method for converting a naturally scalar atomic magnetometer into a vector magnetometer by exploiting the polarization dependence of hyperfine transitions in rubidium atoms. First, we fully determine the polarization ellipse of an applied microwave field using a self-calibrating method, i.e., a method in which the light-atom interaction provides everything required to know the field in an orthogonal laboratory frame...
October 12, 2018: Physical Review Letters
Fangzheng Zhang, Jingzhan Shi, Yu Zhang, De Ben, Lijun Sun, Shilong Pan
Phase noise analyzers (PNAs) are indispensable for evaluating the short-term stability of microwave signals. In this Letter, a high-sensitivity PNA with self-calibration capability is proposed based on an optical frequency comb generator and an optical-hybrid-based I/Q detector. The negative factors that result in inaccurate measurement, including the direct component interference, amplitude noises of the microwave signal under test and the laser, and phase noise of the laser, are all eliminated through digital signal processing...
October 15, 2018: Optics Letters
William Salomon, Anne Dolbecq, Catherine Roch-Marchal, Grégoire Paille, Rémi Dessapt, Pierre Mialane, Hélène Serier-Brault
The luminescent [EuW10 O36 ]9- polyoxometalate has been introduced into the cavities of the highly porous zirconium luminescent metal-organic framework UiO-67 via a direct synthesis approach, affording the EuW10 @UiO-67 hybrid. Using a combination of techniques (TGA, BET, elemental analysis, EDX mapping,…) this new material has been fully characterized, evidencing that it contains only 0.25% in europium and that the polyoxometalate units are located inside the octahedral cavities and not at the surface of the UiO-67 crystallites...
2018: Frontiers in Chemistry
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